The cracked wings of the Airbus A380 double-decker airliner are the result of new technologies mixed with insufficient design controls that are now causing spiraling repair costs, Chief Executive Officer Tom Enders said.

"This is something that wasn't on our radar screen," Enders said of the period 10 years ago when jet designers sought to make A380 wings lighter by mixing carbon fiber and metal. "We thought we understood the properties of the materials and the interface between carbon fiber and metal and found out the wrong way we didn't know everything."

The cracks have forced Airbus to take more than a quarter of a billion euros in repair charges, and the company said this month that fixing its flagship airliner will occupy Airbus for years to come.

Airbus is reviewing its delivery schedule for this year, and said that handing over 30 of the world's largest passenger jet this year will be a challenge.

While taking risks with new materials and programs is a requirement in the airliner business, Airbus didn't have the necessary controls to anticipate potential missteps, Enders told journalists Thursday at a briefing in Toulouse in southwestern France, where Airbus is based.

Airbus also indicated it is slowing a planned ramp-up of production on the single-aisle A320, The Wall Street Journal reported.

The company expects to reach a rate of 42 per month this year, but plans to increase the pace to 44 a month are on indefinite hold due to uncertainty about the world economy, the availability of financing for airline customers, and the supply chain.

"At the moment, we're saying 42 is enough and... we'll pause," said Tom Williams, Airbus's executive vice president for programs, the Journal reported. "We'll wait and see how the market develops."

European Aeronautic, Defence & Space Co., the parent of Airbus, said last week that charges in 2012 alone for a permanent fix for existing A380 wings would total 260 million euros, and that Airbus will take further charges in future years as it assumes the costs of repairing A380 wingsets.

Airbus has traced the cause of the cracks to the choice of a less flexible aluminum alloy used to make the wing brackets, as well as the way in which fasteners are put through holes, and the stresses involved in fitting portions of the wing together.

A short-term fix that takes about five days has been applied to about a third of the 74 A380s in service today. That solution will be applied to other operating A380s as the number of landings and takeoffs reaches a threshold mandated by regulators that requires the fix.

Airbus has worked out a redesign of the wing that would eliminate future cracks and the company is working with the European Aviation Safety Agency to gain approval.

The new design wouldn't work its way into wing structures being built in Broughton, Wales, until mid 2013, meaning the first A380s to come off the final assembly line in Toulouse with the improved wing would be early 2014, Williams said.

Until a permanent redesign is incorporated into future planes, those A380s flying today and entering service before 2014 will need fixes made to wings that are far more complex and time-consuming than the rapid change, Williams said.

Those fixes can either be done after planes are fully built and not yet delivered, or after delivery, with the fixes scheduled to occur during maintenance visits after two and four years, Williams said.

The scheduling for such fixes is now the subject of negotiations with airlines, he said.

"I'm quite sure the A380 will survive this, as other aircraft programs have in the past, but it costs the company dearly in money, and I'm afraid also in reputation," Enders said.